// DHCP Library v0.3 - April 25, 2009
// Author: Jordan Terrell - blog.jordanterrell.com

#include "utility/w5500.h"

#include <string.h>
#include <stdlib.h>
#include "Dhcp.h"
//#include "Arduino.h"
#include "utility/util.h"

int DhcpClass::beginWithDHCP(uint8_t *mac, unsigned long timeout, unsigned long responseTimeout)
{
    _dhcpLeaseTime = 0;
    _dhcpT1 = 0;
    _dhcpT2 = 0;
    _lastCheck = 0;
    _timeout = timeout;
    _responseTimeout = responseTimeout;

    // zero out _dhcpMacAddr
    memset(_dhcpMacAddr, 0, 6);
    reset_DHCP_lease();

    memcpy((void *)_dhcpMacAddr, (void *)mac, 6);
    _dhcp_state = STATE_DHCP_START;
    return request_DHCP_lease();
}

void DhcpClass::reset_DHCP_lease()
{
    // zero out _dhcpSubnetMask, _dhcpGatewayIp, _dhcpLocalIp, _dhcpDhcpServerIp, _dhcpDnsServerIp
    memset(_dhcpLocalIp, 0, 20);
}

//return:0 on error, 1 if request is sent and response is received
int DhcpClass::request_DHCP_lease()
{

    uint8_t messageType = 0;



    // Pick an initial transaction ID
    _dhcpTransactionId = random(1UL, 2000UL);
    _dhcpInitialTransactionId = _dhcpTransactionId;

    _dhcpUdpSocket.stop();
    if (_dhcpUdpSocket.begin(DHCP_CLIENT_PORT) == 0)
    {
        // Couldn't get a socket
        return 0;
    }

    presend_DHCP();

    int result = 0;

    unsigned long startTime = millis();

    while(_dhcp_state != STATE_DHCP_LEASED)
    {
        if(_dhcp_state == STATE_DHCP_START)
        {
            //Serial.println("DHCP_START");
            _dhcpTransactionId++;

            send_DHCP_MESSAGE(DHCP_DISCOVER, ((millis() - startTime) / 1000));
            _dhcp_state = STATE_DHCP_DISCOVER;
        }
        else if(_dhcp_state == STATE_DHCP_REREQUEST)
        {
            _dhcpTransactionId++;
            send_DHCP_MESSAGE(DHCP_REQUEST, ((millis() - startTime) / 1000));
            _dhcp_state = STATE_DHCP_REQUEST;
        }
        else if(_dhcp_state == STATE_DHCP_DISCOVER)
        {
            uint32_t respId;

            messageType = parseDHCPResponse(_responseTimeout, respId);
            if(messageType == DHCP_OFFER)
            {

                // We'll use the transaction ID that the offer came with,
                // rather than the one we were up to
                _dhcpTransactionId = respId;
                send_DHCP_MESSAGE(DHCP_REQUEST, ((millis() - startTime) / 1000));
                _dhcp_state = STATE_DHCP_REQUEST;
            }
        }
        else if(_dhcp_state == STATE_DHCP_REQUEST)
        {
            uint32_t respId;
            messageType = parseDHCPResponse(_responseTimeout, respId);
            if(messageType == DHCP_ACK)
            {
                _dhcp_state = STATE_DHCP_LEASED;
                result = 1;
                //use default lease time if we didn't get it
                if(_dhcpLeaseTime == 0)
                {
                    _dhcpLeaseTime = DEFAULT_LEASE;
                }
                //calculate T1 & T2 if we didn't get it
                if(_dhcpT1 == 0)
                {
                    //T1 should be 50% of _dhcpLeaseTime
                    _dhcpT1 = _dhcpLeaseTime >> 1;
                }
                if(_dhcpT2 == 0)
                {
                    //T2 should be 87.5% (7/8ths) of _dhcpLeaseTime
                    _dhcpT2 = _dhcpT1 << 1;
                }
                _renewInSec = _dhcpT1;
                _rebindInSec = _dhcpT2;
            }
            else if(messageType == DHCP_NAK)
                _dhcp_state = STATE_DHCP_START;
        }

        if(messageType == 255)
        {
            messageType = 0;
            _dhcp_state = STATE_DHCP_START;
        }

        if(result != 1 && ((millis() - startTime) > _timeout))
            break;
    }

    // We're done with the socket now
    _dhcpUdpSocket.stop();
    _dhcpTransactionId++;

    return result;
}

void DhcpClass::presend_DHCP()
{
}

void DhcpClass::send_DHCP_MESSAGE(uint8_t messageType, uint16_t secondsElapsed)
{
    uint8_t buffer[32];
    memset(buffer, 0, 32);
    IPAddress dest_addr( 255, 255, 255, 255 ); // Broadcast address

    if (-1 == _dhcpUdpSocket.beginPacket(dest_addr, DHCP_SERVER_PORT))
    {
        // FIXME Need to return errors
        return;
    }

    buffer[0] = DHCP_BOOTREQUEST;   // op
    buffer[1] = DHCP_HTYPE10MB;     // htype
    buffer[2] = DHCP_HLENETHERNET;  // hlen
    buffer[3] = DHCP_HOPS;          // hops

    // xid
    unsigned long xid = htonl(_dhcpTransactionId);
    memcpy(buffer + 4, &(xid), 4);

    // 8, 9 - seconds elapsed
    buffer[8] = ((secondsElapsed & 0xff00) >> 8);
    buffer[9] = (secondsElapsed & 0x00ff);

    // flags
    unsigned short flags = htons(DHCP_FLAGSBROADCAST);
    memcpy(buffer + 10, &(flags), 2);

    // ciaddr: already zeroed
    // yiaddr: already zeroed
    // siaddr: already zeroed
    // giaddr: already zeroed

    //put data in w5500 transmit buffer
    _dhcpUdpSocket.write(buffer, 28);

    memset(buffer, 0, 32); // clear local buffer

    memcpy(buffer, _dhcpMacAddr, 6); // chaddr

    //put data in w5500 transmit buffer
    _dhcpUdpSocket.write(buffer, 16);

    memset(buffer, 0, 32); // clear local buffer

    // leave zeroed out for sname && file
    // put in w5500 transmit buffer x 6 (192 bytes)

    for(int i = 0; i < 6; i++)
    {
        _dhcpUdpSocket.write(buffer, 32);
    }

    // OPT - Magic Cookie
    buffer[0] = (uint8_t)((MAGIC_COOKIE >> 24) & 0xFF);
    buffer[1] = (uint8_t)((MAGIC_COOKIE >> 16) & 0xFF);
    buffer[2] = (uint8_t)((MAGIC_COOKIE >> 8) & 0xFF);
    buffer[3] = (uint8_t)(MAGIC_COOKIE & 0xFF);

    // OPT - message type
    buffer[4] = dhcpMessageType;
    buffer[5] = 0x01;
    buffer[6] = messageType; //DHCP_REQUEST;

    // OPT - client identifier
    buffer[7] = dhcpClientIdentifier;
    buffer[8] = 0x07;
    buffer[9] = 0x01;
    memcpy(buffer + 10, _dhcpMacAddr, 6);

    // OPT - host name
    buffer[16] = hostName;

    if(_customHostname == 0)
    {
        // use default hostname
        buffer[17] = strlen(HOST_NAME) + 6; // length of hostname + last 3 bytes of mac address
        strcpy((char *) & (buffer[18]), HOST_NAME);
        printByte((char *) & (buffer[24]), _dhcpMacAddr[3]);
        printByte((char *) & (buffer[26]), _dhcpMacAddr[4]);
        printByte((char *) & (buffer[28]), _dhcpMacAddr[5]);
        _dhcpUdpSocket.write(buffer, 30);
    }
    else
    {
        // use custom hostname
        buffer[17] = strlen(_customHostname); // length of _customHostname
        _dhcpUdpSocket.write(buffer, 18);
        _dhcpUdpSocket.write((const uint8_t *)_customHostname, strlen(_customHostname));
    }

    if(messageType == DHCP_REQUEST)
    {
        buffer[0] = dhcpRequestedIPaddr;
        buffer[1] = 0x04;
        buffer[2] = _dhcpLocalIp[0];
        buffer[3] = _dhcpLocalIp[1];
        buffer[4] = _dhcpLocalIp[2];
        buffer[5] = _dhcpLocalIp[3];

        buffer[6] = dhcpServerIdentifier;
        buffer[7] = 0x04;
        buffer[8] = _dhcpDhcpServerIp[0];
        buffer[9] = _dhcpDhcpServerIp[1];
        buffer[10] = _dhcpDhcpServerIp[2];
        buffer[11] = _dhcpDhcpServerIp[3];

        //put data in w5500 transmit buffer
        _dhcpUdpSocket.write(buffer, 12);
    }

    buffer[0] = dhcpParamRequest;
    buffer[1] = 0x06;
    buffer[2] = subnetMask;
    buffer[3] = routersOnSubnet;
    buffer[4] = dns;
    buffer[5] = domainName;
    buffer[6] = dhcpT1value;
    buffer[7] = dhcpT2value;
    buffer[8] = endOption;

    //put data in w5500 transmit buffer
    _dhcpUdpSocket.write(buffer, 9);

    _dhcpUdpSocket.endPacket();
}

uint8_t DhcpClass::parseDHCPResponse(unsigned long responseTimeout, uint32_t &transactionId)
{
    uint8_t type = 0;
    uint8_t opt_len = 0;

    unsigned long startTime = millis();



    while(_dhcpUdpSocket.parsePacket() <= 0)
    {
        if((millis() - startTime) > responseTimeout)
        {

            return 255;
        }
        delay_ms(50);
    }

    // start reading in the packet
    RIP_MSG_FIXED fixedMsg;
    _dhcpUdpSocket.read((uint8_t *)&fixedMsg, sizeof(RIP_MSG_FIXED));

    if(fixedMsg.op == DHCP_BOOTREPLY && _dhcpUdpSocket.remotePort() == DHCP_SERVER_PORT)
    {
        transactionId = ntohl(fixedMsg.xid);
        if(memcmp(fixedMsg.chaddr, _dhcpMacAddr, 6) != 0 || (transactionId < _dhcpInitialTransactionId) || (transactionId > _dhcpTransactionId))
        {
            // Need to read the rest of the packet here regardless
            _dhcpUdpSocket.flush();
            return 0;
        }

        memcpy(_dhcpLocalIp, fixedMsg.yiaddr, 4);

        // Skip to the option part
        // Doing this a byte at a time so we don't have to put a big buffer
        // on the stack (as we don't have lots of memory lying around)
        for (int i = 0; i < (240 - (int)sizeof(RIP_MSG_FIXED)); i++)
        {
            _dhcpUdpSocket.read(); // we don't care about the returned byte
        }

        while (_dhcpUdpSocket.available() > 0)
        {
            switch (_dhcpUdpSocket.read())
            {
            case endOption :

                break;

            case padOption :

                break;

            case dhcpMessageType :

                opt_len = _dhcpUdpSocket.read();
                type = _dhcpUdpSocket.read();
                break;

            case subnetMask :

                opt_len = _dhcpUdpSocket.read();
                _dhcpUdpSocket.read(_dhcpSubnetMask, 4);
                break;

            case routersOnSubnet :

                opt_len = _dhcpUdpSocket.read();
                _dhcpUdpSocket.read(_dhcpGatewayIp, 4);
                for (int i = 0; i < opt_len - 4; i++)
                {
                    _dhcpUdpSocket.read();
                }
                break;

            case dns :

                opt_len = _dhcpUdpSocket.read();
                _dhcpUdpSocket.read(_dhcpDnsServerIp, 4);
                for (int i = 0; i < opt_len - 4; i++)
                {
                    _dhcpUdpSocket.read();
                }
                break;

            case dhcpServerIdentifier :

                opt_len = _dhcpUdpSocket.read();
                if(((_dhcpDhcpServerIp[0] == 0) && (_dhcpDhcpServerIp[1] == 0) && (_dhcpDhcpServerIp[2] == 0) && (_dhcpDhcpServerIp[3] == 0))  || (IPAddress(_dhcpDhcpServerIp) == _dhcpUdpSocket.remoteIP()))
                {
                    _dhcpUdpSocket.read(_dhcpDhcpServerIp, sizeof(_dhcpDhcpServerIp));
                }
                else
                {
                    // Skip over the rest of this option
                    while (opt_len--)
                    {
                        _dhcpUdpSocket.read();
                    }
                }
                break;

            case dhcpT1value :

                opt_len = _dhcpUdpSocket.read();
                _dhcpUdpSocket.read((uint8_t *)&_dhcpT1, sizeof(_dhcpT1));
                _dhcpT1 = ntohl(_dhcpT1);
                break;

            case dhcpT2value :

                opt_len = _dhcpUdpSocket.read();
                _dhcpUdpSocket.read((uint8_t *)&_dhcpT2, sizeof(_dhcpT2));
                _dhcpT2 = ntohl(_dhcpT2);
                break;

            case dhcpIPaddrLeaseTime :

                opt_len = _dhcpUdpSocket.read();
                _dhcpUdpSocket.read((uint8_t *)&_dhcpLeaseTime, sizeof(_dhcpLeaseTime));
                _dhcpLeaseTime = ntohl(_dhcpLeaseTime);
                _renewInSec = _dhcpLeaseTime;
                break;

            default :

                opt_len = _dhcpUdpSocket.read();
                // Skip over the rest of this option
                while (opt_len--)
                {
                    _dhcpUdpSocket.read();
                }
                break;
            }
        }
    }

    // Need to skip to end of the packet regardless here
    _dhcpUdpSocket.flush();

    return type;
}

void DhcpClass::setCustomHostname(char *hostname)
{
    _customHostname = hostname;
}

/*
    returns:
    0/DHCP_CHECK_NONE: nothing happened
    1/DHCP_CHECK_RENEW_FAIL: renew failed
    2/DHCP_CHECK_RENEW_OK: renew success
    3/DHCP_CHECK_REBIND_FAIL: rebind fail
    4/DHCP_CHECK_REBIND_OK: rebind success
*/
int DhcpClass::checkLease()
{
    //this uses a signed / unsigned trick to deal with millis overflow
    unsigned long now = millis();
    signed long snow = (long)now;
    int rc = DHCP_CHECK_NONE;
    if (_lastCheck != 0)
    {
        signed long factor;
        //calc how many ms past the timeout we are
        factor = snow - (long)_secTimeout;
        //if on or passed the timeout, reduce the counters
        if ( factor >= 0 )
        {
            //next timeout should be now plus 1000 ms minus parts of second in factor
            _secTimeout = snow + 1000 - factor % 1000;
            //how many seconds late are we, minimum 1
            factor = factor / 1000 + 1;

            //reduce the counters by that mouch
            //if we can assume that the cycle time (factor) is fairly constant
            //and if the remainder is less than cycle time * 2
            //do it early instead of late
            if(_renewInSec < factor * 2 )
                _renewInSec = 0;
            else
                _renewInSec -= factor;

            if(_rebindInSec < factor * 2 )
                _rebindInSec = 0;
            else
                _rebindInSec -= factor;
        }

        //if we have a lease but should renew, do it
        if (_dhcp_state == STATE_DHCP_LEASED && _renewInSec <= 0)
        {
            _dhcp_state = STATE_DHCP_REREQUEST;
            rc = 1 + request_DHCP_lease();
        }

        //if we have a lease or is renewing but should bind, do it
        if( (_dhcp_state == STATE_DHCP_LEASED || _dhcp_state == STATE_DHCP_START) && _rebindInSec <= 0)
        {
            //this should basically restart completely
            _dhcp_state = STATE_DHCP_START;
            reset_DHCP_lease();
            rc = 3 + request_DHCP_lease();
        }
    }
    else
    {
        _secTimeout = snow + 1000;
    }

    _lastCheck = now;
    return rc;
}

IPAddress DhcpClass::getLocalIp()
{
    return IPAddress(_dhcpLocalIp);
}

IPAddress DhcpClass::getSubnetMask()
{
    return IPAddress(_dhcpSubnetMask);
}

IPAddress DhcpClass::getGatewayIp()
{
    return IPAddress(_dhcpGatewayIp);
}

IPAddress DhcpClass::getDhcpServerIp()
{
    return IPAddress(_dhcpDhcpServerIp);
}

IPAddress DhcpClass::getDnsServerIp()
{
    return IPAddress(_dhcpDnsServerIp);
}

void DhcpClass::printByte(char *buf, uint8_t n )
{
    char *str = &buf[1];
    buf[0] = '0';
    do
    {
        unsigned long m = n;
        n /= 16;
        char c = m - 16 * n;
        *str-- = c < 10 ? c + '0' : c + 'A' - 10;
    }
    while(n);
}
